A known method of thermal treatment, pasteurization, involves heating a filling material for a short period to temperatures of up to 100° C. to increase their shelf life. This, and similar processes, are carried out in thermal-treatment devices.
In an effort to save energy costs, known thermal-treatment devices include a heat exchanger having a primary and secondary side. Filling material that has been pasteurized flows through the primary side. Filling material that has yet to be pasteurized flows through the secondary side. This reduces the energy required to pasteurize by making use of residual thermal energy that flows from the primary side to the secondary side.
One disadvantage of known thermal-treatment devices is that one cannot use as much of the residual heat as one would like. This is because of limits in economically feasible sizes of the heat exchanger. As a result, only a limited portion of the available residual thermal energy from the pasteurized filling material can be transferred to the yet to be pasteurized filling material.